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AD623 Production
The AD623 is an integrated, single- or dual-supply instrumentation amplifier that delivers rail-to-rail output swing using supply voltages from 2.7 V to...
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AD623 on Analog.com

AD8561 Production
The AD8561 is a single 7 ns comparator with separate input and output sections. Separate supplies enable the input stage to be operated from ±5 V dual...
Datasheet
AD8561 on Analog.com

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Problems interfacing AD623 with AD8561 comparator.



		

			

									
					    cholmste
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Sep 22, 2011 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    I ran into an issue when interfacing the AD623 with the AD8561 comparator.
    
 
    Pin 3 of the comparator (negative input) is 'feeding' or is biased at ~1.4V. This seems to cause problems with the AD623 driving the input of the comparator.
    
 
    The AD623 can drive loads of 10kohm or greater.
    
 
    The AD8561 has a PNP differential stage input.
    
 
    Does this means that the AD623 output is incompatible with the AD8561 input and an extra buffer is needed between the two?
    
 
    Thank you in advance.
    
 
    Christian